The present invention relates to structures, such as doors, for controlling passageways, through openings in structural walls where such control structures are formed with outer coverings of a polymeric material and, more particularly, to such structures which must withstand extremes of temperature and other environmental factors.
Building structures are erected to separate the contents and inhabitants thereof from the external environment. Access control means in openings provided in such building structures, including windows and doors, control the passage of air, water, people and numerous other entities into and out of such a structure.
Such doors and windows must have a close fit within the frames provided therefor in these structural building openings if they are to successfully control passage of substantially all air and water therethrough. Doors must also be sufficiently strong to withstand substantial bumping as various kinds of objects are moved near and through the passageway in which the door is provided, to withstand slamming by users of the door, etc. Both doors and windows must withstand buffeting by storms, and also must remain operable over what are often extensive temperature ranges. In addition, they must withstand the deteriorating effects of great variations in weather over long periods of time while, in many instances, also retaining acceptable appearance characteristics.
As a result, a number of different kinds of materials have been used for exterior doors and windows, such as storm doors, in efforts to provide satisfactory designs for these needs. Thus, storm doors have been constructed of assembled wooden parts, aluminum parts, or vinyl parts, and often of combinations of these materials. In addition, various other polymer-based materials have been used.
The door and window structures resulting from the use of these materials have had various shortcomings most often caused by the undesirable structural and thermal characteristics of the materials being used or by the construction methods employed in using these materials. Some of the materials so used have had, for instance, an unacceptably large coefficient of thermal expansion. Such coefficients prevent the products formed from them from having close fits in structural opening frames with small tolerances over various temperature and weather conditions, and further, lead to door warpage particularly in the presence of temperature gradients. A storm door can not only experience in use at times temperatures of 40.degree. to 50.degree. F. below zero, but can at other times be subjected to temperatures which will be 140.degree. F. on an exterior surface in direct sunlight and 200.degree. F. on an interior surface due to a "greenhouse effect" occurring between the storm door and the entry door in a building.
With such temperature ranges, excessive coefficients of thermal expansion mean the doors cannot be closely fitted in the frames or there will be insufficient room for thermal expansion and contraction. Too close a fit will lead to the door sticking, warping or otherwise bending. Yet, large tolerances in the fit between the door and the frame mean that undesired passage of air from one side of the door to the other is unavoidable. Even with large tolerances in the fit, temperature differences can occur in the door which will still lead to its sticking, warping or otherwise bending.
Various construction techniques have been applied in forming doors and windows in attempts to overcome the shortcomings therein due to the materials used. Such techniques often involve additional fasteners or stiffening means which must be incorporated and usually lead to increased costs.
In these circumstances, access control means such as doors are desired which will be capable of being installed with a close fit between themselves and the frames about the structural wall openings for which they are provided, and which can be maintained in all weather conditions including extreme temperature ranges. The outer surfaces thereof should be able to be embossed to have an appearance which is compatible with other materials being used in the building structure for the siding, facia, soffits, etc. Yet these surfaces should be resistant to deterioration or physical damage, and to moisture, while retaining protective and decorative coatings provided thereon to thereby minimize required maintenance efforts. Parts of some access control means at or near such surfaces should be magnetizable to permit use thereof with magnetic weather stripping. Further, the structures used for such items should not require use of unduly expensive fabrication methods and materials.